1. Field of the Invention
The present invention relates to a stereomicroscope, and particularly relates to a stereomicroscope by which two observers can simultaneously observe an object.
2. Description of the Related Art
In general, a stereomicroscope is a microscope that enables observation of an object as it is without processing it into a thinly sliced specimen, etc. Some stereomicroscopes enable two observers to observe an object simultaneously. An example of such a stereomicroscope is a surgical microscope used in the medical field (particularly in the ophthalmology, neurosurgery, etc.).
Japanese Unexamined Patent Application Publications Nos. 2000-330032, 2004-226828 and 2005-137577 disclose conventional stereomicroscopes (surgical microscopes). The stereomicroscopes described in Japanese Unexamined Patent Application Publications Nos. 2000-330032 and 2004-226828 each have an operator's microscope and an assistant's microscope. The assistant's microscope is disposed rotatably around the center of an objective lens with respect to the operator's microscope.
Part of an optical system of the stereomicroscope is shown in FIGS. 13 and 14. A stereomicroscope 1000 is an apparatus for observing a magnified image of an observation object 2000. The stereomicroscope 1000 comprises a primary observation optical system 1010 and a secondary observation optical system 1020 as well as an illumination optical system, which is not shown.
In a surgical microscope, the primary observation optical system 1010 is an optical system of a microscope used by the operator. Further, the secondary observation optical system 1020 is an optical system for an assistant's microscope used by an assistant. In FIG. 13, the operator is on the rear of paper (behind an objective lens 1001) and observes the observation object 2000 while facing the front of the paper. The assistant is on the right or left side of the operator. The illumination optical system is placed on the front side of the paper of FIG. 13.
The illumination optical system is an optical system for projecting an illumination light onto the observation object 2000. The illumination optical system includes a reflecting mirror 1031 shown in FIG. 14, and additionally includes optical elements, which are not shown, such as a light source, an aperture and a lens. The reflecting mirror 1031 is placed immediately above the objective lens 1001. The reflecting mirror 1031 reflects an illumination light outputted from the light source, and projects it onto the observation object 2000 via the objective lens 1001.
The primary observation optical system 1010 guides the illumination light reflected by the observation object 2000 to an operator's ocular lens (not shown). The primary observation optical system 1010 is provided with a pair of optical systems on the right and left. Thus, stereoscopic observation with both eyes becomes possible.
The primary observation optical system 1010 is provided with variable magnification lenses (zoom lenses) 1021L and 1021R, and additionally, various kinds of optical elements, which are not shown.
The secondary observation optical system 1020 guides the illumination light reflected by the observation object 2000 to an assistant's ocular lens (not shown). The secondary observation optical system 1020 is also provided with a pair of optical systems on the right and left, whereby stereoscopic observation with both eyes becomes possible. The secondary observation optical system 1020 is provided with various kinds of optical members such as a reflecting member 1022 provided immediately above the periphery of the objective lens 1001 and a lens 1021.
The primary observation optical system 1010 is placed so that right and left optical axes OL and OR become parallel to an optical axis O of the objective lens 1001 (at least adjacent to the objective lens 1001). In addition, the secondary observation optical system 1020 is placed so that an optical axis OP thereof becomes orthogonal to the optical axis O of the objective lens 1001.
The secondary observation optical system 1020 is configured so that the position thereof with respect to the primary observation optical system 1010 can be changed in order to enable the assistant to change his/her position. To be specific, the secondary observation optical system 1020 is configured so as to be rotatable around the optical axis O of the objective lens 1001. The secondary observation optical system 1020 rotates around the optical axis O along a trajectory T shown in FIG. 14. Thus, the assistant can observe while being on the right or left side of the operator. Symbols FL and FR in FIG. 14 denote observation fields by the right and left optical systems of the primary observation optical system 1010.
Further, in some conventional stereomicroscopes, right and left observation fields of the primary observation optical system are arranged asymmetrically with respect to the center of the objective lens, and a reflecting member (equivalent to the abovementioned reflecting member 1022) that guides a reflected light from an observation object to the secondary observation optical system is arranged in the center of the objective lens.
Further, Japanese Unexamined Patent Application Publication No. 2005-37577 discloses a stereomicroscope configured so that the secondary observation optical system itself is capable of swiveling upward and thereby the observation position of the assistant can be switched to the right and left.
The conventional stereomicroscopes as described above have the following problems.
Firstly, regarding the stereomicroscope shown in FIGS. 13 and 14, when the secondary observation optical system 1020 is rotated, the reflecting member and a member that supports it may block the observation fields FL and FR of the operator.
Further, in some stereomicroscopes, the secondary observation optical system 1020 is configured to be attachable to and detachable from a lens tube 1040. It takes time and labor to manually change the position of the secondary observation optical system 1020, and moreover, the structure of an attachment/detachment part is complicated.
Further, regarding the stereomicroscope in which the right and left observation fields of the primary observation optical system are arranged asymmetrically with respect to the center of the objective lens, the observation object is observed from an oblique direction. Therefore, a burden may be imposed on the operator.
Further, regarding the stereomicroscopes in which the secondary observation optical system is configured to be capable of swiveling upward, the shape of the lens tube of the primary observation optical system is limited, and a complicated rotating mechanism is required.
Additionally, since various instruments are installed in an observation room such as an operating room, the swiveling secondary observation optical system may hit objects and people.